Keratinaceous materials are often included in animal feeds as an inexpensive source of dietary protein. Keratins such as feather, horn, hooves, and hair are readily available as agricultural byproducts. A problem with feeding animals such materials, however, is that they are difficult to digest. J. Adler-Nissen, Enzymic Hydrolysis of Food Proteins, 100 (1986). Hence, the amount of amino acids taken up into animals from such materials is relatively small compared to the total amount of amino acids present in such materials.
A solution to the foregoing problem is reported in U.S. Pat. No. 4,908,220 to J. Shih and C. Williams, issued Mar. 13, 1990. This patent describes a hydrolyzed feather animal feed supplement consisting of feather hydrolyzed by fermenting it with Bacillus licheniformis PWD-1 prior to feeding the material to the animal. While the technology disclosed in this application provides a way to substantially increase the digestability of feather, it necessitates a fermentation step which adds to the complexity of manufacturing the feed.
In view of the foregoing, an object of the present invention is to provide a way to increase the digestibility of keratin, which keratin is included in an animal feed as a source of dietary protein, without the necessity of fermenting the material prior to feeding.